Presently, various resins are used to produce numerous types and styles of pipe. For example, polyethylene resins have long been used to produce high stiffness pipe used in water, gas, and other fluid transport applications. Polyethylene pipe classified as PE-100, MRS 10, or ASTM D3350 typical cell classification 345566C is especially desirable for use under conditions requiring higher pressure ratings. The higher pressure ratings are due in part to the pipe's higher stiffness. To obtain a PE-100 classification, PE-100 pipe is required to meet certain standards specifying stiffness, resistance to chemical attack, and brittleness, as expressed as rapid crack propagation under cold temperature environments or applications. Further, such pipe must meet a deformation standard which is determined under pressure at elevated temperatures. Resin which can be employed to produce both small diameter (1 inch to 12 inches in diameter) and large diameter (greater than 12 inches in diameter) PE-100 pipe is described in U.S. patent Ser. No. 10/373,648, which is incorporated herein by reference in its entirety.
It is also desirable for PE-100 pipe to exhibit toughness. This characteristic can be important in many polyethylene pipe applications, such as, where the pipe is buried underground or where the pipe is used to transport abrasive slurries. For example, gravel or crushed ore is often moved in mining operations through PE pipe as a high-velocity aqueous slurry. Such materials can be very abrasive to the pipe; thus, pipe toughness becomes highly valued. Accordingly, there is a need for a resin and a PE-100 pipe made therefrom which has an improved abrasion resistance.
This invention relates to polyolefin compositions, methods for producing polyolefin compositions, and to processes for using polyolefin compositions for producing pipe and other articles of manufacture having an improved abrasion resistance. More specifically, this invention relates to the production of PE-100 classification polyethylene pipe and the resin used to make such pipe which have improved abrasion resistance.